1. Field of the Invention
The present invention relates to a pneumatic tire which can discharge a static electricity generated in a vehicle body and a tire, to a road surface.
2. Description of the Related Art
In recent years, there has been proposed a pneumatic tire in which a rubber member such as a tread rubber or a side wall rubber is formed by a nonconductive rubber which is blended with a silica at a high ratio, in order to reduce rolling resistance of the tire which has a close relationship with fuel consumption efficiency. However, compared to a conventional rubber member blended with carbon black at a high ratio, such a rubber member has a higher electric resistance, and therefore static charge generated on a vehicle body or a tire is prevented from being released to a road surface. As a result, a problem such as radio noises tends to occur.
Accordingly, there has been developed a pneumatic tire which can achieve electrical conduction performance by setting a conductive portion which is made of a conductive rubber blended with carbon black or the like, while forming a tread rubber and a side wall rubber by a nonconductive rubber. For example, in a pneumatic tire described in the following Japanese Unexamined Patent Publication No. 2008-296634, a band-like rubber strip constructed by a conductive rubber is arranged so as to extend to an inner side in a tire diametrical direction from a tread rubber and reach a clinch rubber (a rim strip rubber), and a conductive route for discharging a static electricity is formed.
However, in the tire mentioned above, since the band-like rubber strip is exposed to an outer surface of a bead portion or a bead bottom surface, and it comes into direct contact with a rim, an exposure end portion of the rubber strip tends to wear out due to a rim friction, and there is a risk that an electrical conduction performance is adversely affected. In addition, in order to secure an effect of improving a rolling resistance, it is desirable to reduce a volume of a conductive rubber not only in a tread rubber and a side wall rubber, but also in a rim strip rubber.